Using the Einstein-Cartan-Dirac theory, we study the effect of torsion on
neutrino oscillation. We see that torsion cannot induce neutrino oscillation,
but affects it whenever oscillation exists for other reasons. We show that the
torsion effect on neutrino oscillation is as important as the neutrino mass
effect, whenever the ratio of neutrino number density to neutrino energy is
∼1069 cm−3 /eV, or the number density of the matter is ∼1069 cm−3.Comment: 7 pages, LaTex,Some typos corrected Journal: Int. J. Mod. Phys. A
(1999) (will be appeared